This invention relates to systems for the automated or computer-controlled manipulation of flexible sheet or limp material segments. More particularly, this invention relates to a device for automatically lifting flexible sheet or limp material segments from a support. The invention is particularly well adapted for use in automated textile garment assembly systems where it is important to reliably lift a single sheet.
The complex textile manipulations required in the assembly of garments are typically performed manually, causing them to be very labor-intensive. As a result, labor costs are high, causing the resulting clothing products to be expensive. The automation of garment assembly would be of great economic value by providing a more efficient and less expensive mode of manufacture.
Various mechanical devices have been used in the prior art for automated cloth manipulation, but problems have accompanied their usefulness. For example, articulated robotics, although being quite capable of moving rigid objects, have not been as successful in handling more flexible objects such as cloth. Some automated textile handling devices use teeth, pinchers, needles, or other moving parts. These devices often damage the fabric during manipulation, for example, by snagging, tearing, stretching, or creasing of the fabric. These devices may also damage the textile supporting work surface. For example, if the teeth or needles of the device should impale the cloth or miss it completely, the wear on the work surface is accelerated.
In addition, the separation of a single ply of limp fabric from the top of a stack of such plies has not been satisfactorily accomplished with the prior art devices. Removal of a single ply from a stack of cut plies of a woven fabric is a particularly difficult task to execute, even for human hands, because the edge threads of such plies are often slightly interlocked as a result of being cut together.
Approaches have been taken in the prior art to utilize hollow needles which are automated so as to penetrate and lift the top ply of fabric from a stack in part with the assistance of air flow through the needles. In these approaches, the penetration of the needles presents potential for damaging the fabric and work surface.
Other approaches have utilized vacuum flow as a lifting means for example as disclosed in U.S. Pat. No. 4,632,046. However, when such devices are used to lift the top ply of fabric from a stack, typically more than one ply is lifted, particularly when the fabric is permeable to airflow.
Accordingly, it is an object of the present invention to provide an improved system of automated cloth manipulation to be used in article assembly.
Another object is to provide an automated system of cloth manipulation which does not damage the cloth.
Yet another object is to provide an automated system of flexible or limp sheet ply separation.
A further object is to provide a non-damaging system of ply separation and manipulation which is inexpensive and efficient.